The invention relates to an exhaust gas catalytic converter and to the use of such device in motor cars or as a stationary apparatus for catalytic afterburning.
The exhaust gas catalytic converter is a component integrated in the exhaust gas system of e.g. a motor vehicle and in which catalytic afterburning takes place. The afterburning breaks down pollutants, namely carbon monoxide, hydrocarbons and nitrogen oxides, i.e. they are converted to carbon dioxide, nitrogen and water. The afterburning should take place as close as possible to the engine to make use of the warm content of exhaust gases during cold starting without large losses so that the operational temperature (250.degree.-750.degree. C.) is achieved after a warming-up phase which is as short as possible. A known design of the exhaust gas catalytic converter is a monolith, in which a ceramic substrate has a honeycomb structure. This honeycomb structure is formed by a plurality of parallel channels. Because all the channels must have the same length, the honeycomb structure has a substantially cylindrical shape, i.e. cross-sectional surfaces of the honeycomb structure have the same size and the same shape along their whole length.
Due to limited space in the vicinity of a motor car engine, it is usually not possible to integrate an exhaust gas catalytic converter of the known design satisfactorily in the exhaust gas system. The question arises whether there are means which would enable better integration. The basis of the present invention is the realization that such means might actually be available: namely if it were possible to find an exhaust gas catalytic converter which could be shaped more flexibly than known devices. A more flexible shaping would, for instance, enable, in the case of predetermined obstructions in the vicinity of the engine, to form the catalytic converter such that it could be fixed very close to the outlet of exhaust gases from the engine. It is therefore a particular aim of the invention to devise an exhaust gas catalytic converter, possessing this flexibility.